404 as a way to undo earlier webmention

[sandeepshetty]

• delete post
• send webmention
• target gets a 404 and deletes previous webmentions from source
• this is useful for things like unlike

Alternatively, source will delete previous webmentions if it can't find a link to itself on target.

[aaronpk]

Further discussion here: http://indiewebcamp.com/deleted

[barnabywalters]

Even further discussion: http://indiewebcamp.com/deleted-404-discussion